Here are presented the functions of the critical landing door parts that affect elevator safety and also fire safety. The main components are sill, frame, railing, and door panels.
The sill is the base support element of the landing door. The door entrance is fixed to a floor or shaft wall with sill fixing brackets and sill structure. During the elevator lifetime the sill is constantly under dynamic and static forces due to elevator loading and unloading which is why it is important that the sill keeps its rigidity. Between landing door panels and sill there is a running clearance which is allowed to be a maximum of 6 mm with new installations, and after wearing the clearance may be 10 mm. This door bottom running clearance is a potential
leakage source during a fire accident, or fire test. The sill itself has no remarkable role in fire testing as it is behind the concrete floor and only a short portion of it faces direct heat. However, solid aluminum sill profiles might melt during two-hour fire tests. The sill structure with attached toe-guard is shown in figure 10.
The toe-guard is the metal sheet that prevents the elevator from cutting a passenger’s toes off in case of elevator door control failure and the car arrives to floor with its doors open. (Interviews)
Figure 10. Landing door sill and toe-guard
The frame is the piece that supports the whole entrance. It has the interface to the building wall, which can be concrete, dry line wall, or steel shaft, and with base duty doors it includes signalization which is the device that calls the elevator and shows on which floor it currently is. The frame is the part between door panels and entrance wall and typically it carries the railing mechanism. The frame includes insulation if needed but typically it is non-insulated. It includes two vertical uprights and one horizontal lintel part. All of the frame parts are important
in terms of fire integrity. Rigid connection to the wall and to the railing mechanism during fire accident, or testing is essential. The frame assembly can be seen in figure 11 below. (Interviews)
Figure 11. Landing door frame
The railing is the heart of the landing entrance. It includes the locking device which prevents unwanted door opening. If the doors were not locked in case of fire, fire integrity would be lost immediately. This is the reason why all landing doors must be locked when an elevator is not in operation, and the reason why the railing mechanism’s main operation is to keep door panels locked, and during operation to allow doors to open and close. Hanger plates are the contact points for door panels and they include running wheels which make opening and closing the doors possible. The landing door railing is shown in figure 12 with brackets on top. Brackets are used to fix the railing to different types of wall in the same way as the sill and frame assemblies. (Interviews)
Figure 12. Landing door railing mechanism
Panels are the most essential part of the landing door in terms of fire safety and fire integrity. The more panels are used in one entrance system the more challenging task fire integrity becomes. In figure 13 are presented the door panels of a landing door, and in this case there are two panels. For instance, a landing door assembly with only one panel opening to the side is the best type in terms of fire integrity, but on the other hand a six-panel centre-opening door is the most difficult case to handle. (Interviews)
Figure 13. Landing door panels
Between the door panels and between panels and frame there needs to be a fire integrity blocker. This blocker, or limiter, can consist of just a simple steel labyrinth which makes panels, or panel and frame, overlap each other thus preventing gases from leaking from one side to another. If labyrinths are not used, another solution is to use intumescent material, normally heat expanding tape, which is used especially in building doors. Panels may be non-insulated or insulated depending on the fire classification needs. Insulation is typically added to the shaft side of the door construction. (Interviews)
7 FIRE TESTING AND CERTIFICATION
As stated before, elevators possess potential safety hazards if not designed, built, and tested properly. Fire hazards are one of the matters that are almost always supervised by a state’s fire inspector or a governmental body. Unfortunately, more often than not, these supervising bodies do not possess the product know-how, or have the authority to vouch for the product’s safety. Therefore products are tested and certified by trusted parties to ensure safety requirements are fulfilled and supervising bodies are able to check their function from commonly known markings.
KONE fire tests roughly 5-10 landing doors annually. These numbers illustrate the full scale fire tests that are tested by an accredited notified body, and if passed, can be certified accordingly. KONE also tests using smaller scale fire tests solely for testing purposes and also pure material tests. Small scale tests are mostly done to ensure the design of the door is good enough to pass a full scale test, or to check new designs for unseen faults. The total cost of a full scale fire test is approximately 20,000 Euros, a smaller test is much cheaper. The price includes all personnel and material costs from KONE and also certification, assessment and personnel costs of the testing party. (Interviews)